Half to henry martyn robert



(No Model.)

L. DAURIA.

DIRECT ACTING PUMPING ENGINE.

Patented Feb. 17,1891.

Jaye/24 02" Wad/ Minn diaries Parent relics,

LUIGI DAURIA, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE- IIALF .TOHENRY MARTYN ROBERT, OF SAME PLACE.

DlRECT -ACTENG PUMPlNG ENGINE.

SPECIFICATION forming part of Letters Patent No. 4%,435, dated February17, 1891. Application filed February '7, 1888. $erial1l'o. 263,304. (Nomodel.)

To all whom it may concern:

Be it known that I, LUIGI DAURIA, a subject of the King of Italy,residing at Philadelphia, in the State of Pennsylvania, have inventedcertain new and useful Improvementsin Direct-Acting Pumping-Engines, ofwhich the following is a specification.

My invention relates to the general class of direct-acting non-rotativesteam pu mping-engines, single or duplex, simple or compound. Indirect-actin g non-rotative steam pumping engines, especially wheresteam is used expansively, the propelling force of the engineeffectively employed in driving the pump is necessarily from thebeginning up to a certain point of the stroke somewhat greater and forthe remaining part of the stroke somewhat less than the total pressureexerted by the liquid column upon the pump-plunger while in motion.Ilence during the former part of the stroke the excess of the effectivepropelling-force over the resistance of the pump performs an amount ofwork which, being solely expended in producing an acceleration, may beproperly called accelerative work.

During the latter part of the stroke the excess of resistance over theeffective propelling force gives place to a retarding work,

which in a direct-acting non-rotative steam pumping-engine runningsmoothly must be equal to the accelerative work. Otherwise either thestroke will be shorter than normal or the piston will strike thecylinder-head.

Designers of this class of pumping-engines have always considered it tobe absolutely necessary to maintain upon the pn mp-plunger under anycircumstances an effective propelling force practically equal to or veryslightly greater than the resistance of the pump. Consequently whensteam is used expansively in such pumping engines compensating devicesare now employed which practically nullify the accelerative workincident thereto.

The object of my invention is to provide means whereby a direct-actingnon-rotative steam pumping-engine may use steam expansively withoutcompensating devices nullifying or reducing the accelerative work incident thereto. I

In myinvestigation of the problem in ques tion I have satisfied myselfthat the immediate eitect of an increased accelerative work in adirect-acting non-rotative steam pumping-engine is the increase of itspiston speed, andthatwhen this speed exceedsacertainlimit the action ofthe piston becomes concussive and spasmodic. \Vhatever this limit ofpiston speed may be in practice, the problem is to find means wherebythe piston speed maybe regulated and controlled under any grade of steamexpansion without compensating devices. I have found that by adding tothe requisite reciprocating parts of such an engine a supplementalreciprocating weight I can so regulate and control the piston speedunder any accelerative work as to avoid c011- cussion and spasmodicaction. Such means is suggested by a new principle discovered by me,which, so far as canbe expressed in ordinary language, is as follows:

In a direct-acting non-rotative steam pump ing-engine using steamexpansively the mean piston speed in feet per second varies from fourand a half to five times the square root of the accclerative work infoot pounds, as herein defined, divided by the square root of the sum ofthe products obtained by multiplying each of thereciprocatingweightsinpounds set in motion at every stroke by the square of the velocity ofits center of gravity or center of gyration expressed in terms of thevelocity of the piston as unit. This sum of products may, for brevity,be called hereinafter accelerated mean weight. Theoretically theaccelerated mean weight should include the weight of the column of waterconfined between the level of the suction-chamber and the level of theair-chamber multiplied by the square of its velocity expressed in termsof the velocity of the piston as unit; but in practice this portion ofthe accelerated mean Weight, so far as my invention is concerned, issupposed to be only a small fraction of the total, and its being nelected in the computation can only produce a slight difference in thevalue of the mean piston speed.

According to the above principle, in order to obtain a given pistonspeed the accelerated mean weight in pounds must be between twenty andtwenty fivc times the accelerative work in foot pounds divided by thesquare of the given piston speed in feet per second. The number twentycorresponds to the case when the accelerative work is performed by aconstant accelerative force, and the retarding work is performed by auniformlyincreasing retarding force, which would be practically the caseif steam were used expansively in a simple cylinder cutting off at aboutone-half of the stroke. The number twenty-five corresponds to the casewhen the aceelerative work is performed by a uni formly-decreasingaccelerating force and the retarding work by a uniformly-increasingretarding force, as before. Practically this is the case when steam isexpanded in compound cylinders or when'steam is out off very early inthe'stroke.

Forpractical purposes it may bestated that in a direct-actingnon-rotative steam pumping-engine the accelerated mean weight in poundsis approximately equal to twentythree times the accelerative work infoot pounds divided by the square of the mean piston speed in feet persecond.

Now suppose, for example, it is desired to ascertain the acceleratedmean weight in pounds which itis necessary to put upon a direct-actingnon-rotative steam pumping-engine in order to obtain a mean piston speedof two feet per second when steam is cut off at one-third of thestrokein a simple cylinder, the stroke .bein-g three feet, the diameter of theplunger twentyinches, and the total head'two hundred feet. Assuming aneven back-pressure upon the steam-piston and a constant pressure uponthe plunger-while in motion, the accelerative work would be about twelvethousand foot pounds, and consequently the accelerated mean weight wouldbe twenty-three times twelve thousand divided by the square of two, orabout seventy-five thousand pounds. If the weights of the requisiteworking parts of this pumping-engine computed in the manner hereindefined will make up only, say, five thousand pounds of the requiredaccelerated mean weight, then the remaining seventythousand pounds mustbe supplemented by an'additional weight, which, however, may be greatlyreduced, provided its center of gravity or gyration moves with avelocity considerablygreater than that of the piston. In fact, if thevelocity of the center of gravity or gyration of the additional weightis three times greater than that of the piston, then in accordance withthe definition already given of the accelerated mean weighttheadditional weight would have to be about seventy-eight hundred poundsor seventy thousand pounds divided by the square of three.This'pumping-engine without such additional weightwould acquire a meanpiston speed of nearly seven and one-half feet per second, or nearlyfourhundred and fifty feet per minute, which is nearly double the speedattained by the best regulated crank and fly-wheel pumpingspeed theengine of our example would never be able to reach the end of a singlestroke without disastrous consequences, and this may serve to explainthe reason why designers of direct-acting non-rotative steampumping-engines'have settled uponthe condition that under allcircumstances the accelerative work must be reduced to a minimum orpractically nullified. Suppose, for instance, that by means of properdevices the accclerative work, instead of twelve thousand foot pounds,be reduced to, say, twelve hundred foot pounds. Then without additionalweight the mean piston speed in feet per second would according to myprinciple be about four times the square root of twelve hundred dividedby the square root of five thousand, (the latter being the assumedaccelerated mean weight in pounds,) or about two feet per second. Thisis about the maximum piston speed at-which direct-acting non-rotativesteam pumpingengines of large size have ever been run. Now the totalwork absorbed by the pump in a single stroke is about eighty-onethousand foot pounds, of which the accelerative work of twelve hundredfeet pounds only represents about one and one-half per cent. Hence itmay be safely stated that direct-acting nonrotative steampumping-engines as'now constructed could never be made to worksatisfactorily with an accelerative work exceeding two per cent. of thetotal work absorbed by the pump in a single stroke, for under suchconditions, andeven under the conditions assumed, these pumping-engineswould acquire a piston speed far exceeding their-safe limit, and theiraction would become concussive and spasmodic.

\Vith the above percentage of accelerative work the accelerated meanweight inpounds in direct-acting non-rotative steam pumpingengines asheretofore constructed would be limited, therefore, totwenty-three-times two per centum of the total work absorbed by the pumpin a single stroke divided by the square of the mean piston speed infeet per second, or approximately such accelerated mean weight would beequal to one-half of the work infoot pounds absorbed by the pump in asingle stroke divided by the square of the mean piston speedin feet persecond.

In my invention I claim only such directacting non-rotative steampumping-engines whose accelerated mean weight in pounds, as hereindefined, exceeds the quotient obtained by dividing thetotal work in'footpounds absorbed by the pump in a single stroke by the square of the meanpiston speed in feetper second.

In the accompanying drawings I have illustrated one of thevariousmethods which may be used to increase the accelerated meanweight, although I do not confine myself to the details thereof.

Figure 1 is a side elevation, and Fig. 2 is engines of the larger size.lVith such piston an end View, of an ordinaryduplex directactingnon-rotative steam pumping-engine adapted to use steam expansively, inwhich- A and B are the steam-cylinder and the pump-barrel of one side.

B is the pump-barrel of the other side and corresponding to anothersteam-cylinder A. (Not shown.) The pistons of Aand B are, as usual,carried by the same piston-rod O, and it is to be understood that thepistons of A and B are also mounted upon the same pist0n-rod C. (Notshown.)

R and H and R and II are the cranks and shafts, and Z and Z thevibrating arms ordinarily employed in duplex direct-aetingnonrotativesteam pumping-engines to operate the main valves in the steam-chests Sand S, and they are arranged as usual, so that the crank and shaft setin motion by one engine is made to operate the main steam-valvebelonging to the other engine.

L and L are extensions of the arms Z and Z, and are loaded with theweights IV and I for the purpose of increasing the accelerated meanweight. The position of the weights W and \V can, as shown, be shiftedon the arms L and L, and as this shifting affects the accelerated meanweight it will affect also the piston speed, other things remaining thesame.

V and V are cut-oft valves adjusted in the steam-passages of eachsteam-cylinder and derive their motion from the engine to which theybelong.

M and N are connecting-rods, and A the arms attached to the cutoffvalves V of one side to operate said valves. The arms a are slotted inorder to allow the point of cut-off being varied. A similar mechanism isemployed to operate the cut-off valves V of the other side.

hen this particular construction (or any other similar to it) isadopted, then in computing the accelerative work it must be rememberedto subtract the amount of work absorbed by the additional reciprocating;weight \V or IV in the action of being lifted from its lower to itshigher vertical position during the first half of the stroke, which isretarding work. This amount of work in foot pounds is equal to theadditional weight in pounds multiplied by the vertical lift of itscenter of gravity in feet, including the oscillating arm; but theadditional reciprocating weights in my invention are not intended toact, and are not employed as compensating devices in the sense nowunderstood, butsimply as means to control and regulate the mean pistonspeedin the manner and according to the principle set forth. The reason,

however, for preferring such construction is the economy of additionalweight it affords over different constructions which I might otherwiseuseas, for example, the increase of the weight of the pistons andpiston-rods.

The arms Z and Z may be extended downward instead of upward, and anyother convenient form of cutoff valves and mechanism may be adopted.

hat I claim as my invention, and desire to secure by Letters Patent, is

1. The within-described art or method of regulating the mean pistonspeed in a directaeting non-rotative steam-expanding pumping-engine,which consists in adding to the requisite reciprocating parts asupplemental reciprocating weight, which, with the weight of therequisite reciprocating parts, is so proportioned in relation to theaccelerative work, as herein defined, as so to control the accel eratedand retarded motion of the engine that concussion and spasmodic actionshall be avoided.

2. A direct-aeting non-rotative steam-expanding pu mping-en gine adaptedto work under steam expansion sufficient to produce an aecelerativework, as herein defined, exceeding four per cent. of the total workabsorbed by the pump in a single stroke, and provided with an additionalreciprocating weight, which, when in motion with the requisite workingparts, will produce an accelerated mean weight in pounds, as hereindefined, greater than the quotient obtained by dividing the total workin foot pounds absorbed 5 by the pump in a single stroke by the squareof the mean piston speed in feet per second.

3. In combination with a direct-actin g nonrotative steam-expandingpumping-engine, an additional reciprocating weight or weights IOOconnected to and oscillating with the reciprocating parts of thepumping-engine and adapted to control the accelerated and retardedmotion of the engine, thereby preventing concussion and spasmodicaction, sub- 105 stantially as and for the purpose set forth.

4:. In combination with a direct-acting nonrotative steam-expandi n g pum pin g-engine, an additional reciprocating weight or weights, as XV W",fixed or adjustable upon the arms L no and L, oscillating with andconnected to the valve-operating arms I and Z, as shown, and for thepurpose specified.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing r15 witnesses.

LUIGI DAURIA. V Witnesses:

O. A. DOUG-HERTY, W. W. DOUGHERTY.

